Grit distributing apparatus



A ril 10, 1962 R. s. CAMPBELL ETAL 3,028,711

GRIT DISTRIBUTING APPARATUS Filed May 16, 1960 INVENTORS v Faber? S, Campbell 3 v y Eugene A'chul;

United States Patent Ofifice 3,028 ,7 1 l Patented Apr. '10, 1962 3,028,711 GRIT DISTRIBUTING APPARATUS Robert Li. Campbell, Morton Grove, and Eugene A.

Schulz, Arlington Heighta'llL, assignors to Crane Packing Company, Morton Grove, 111., a corporation of Illinois Filed May 16, 1960, Ser. No. 29,228 7 Claims. (Cl. 51263) This invention relates to grit distributing apparatus for lapping machines or the like wherein a liquid vehicle con taining grit in suspension is to be applied to a rotating lap plate continuously in small quantities.

It is customary in lapping machines of a known type which use continuously operating conditioning tools in the form of wear rings, to apply grit to the rotating lap plate of such machines continuously to replace spent grit. Such prior art machine is disclosed in Re. 23,937 to E. J. Bullard dated February 8, 1955, for Lapping Machine. The quantity of new grit to be applied is quite small, and it is conveniently done by suspending the grit in an oily vehicle which is conducted to the lap plate and allowed to drip thereon. The vehicle and grit are stored in a container which is equipped with a stirring device to insure suspension of the grit in the vehicle, and the vehicle is then metered through a small orifice and valve to a wire along which it flows to a selected location over the lap plate. The wire is made to terminate at such location and the grit and vehicle then drip from the end of the wire to the lap plate.

One of the difiiculties encountered with the foregoing system of applying grit to a lap plate is that the orifice, which must necessarily be small to limit the flow of grit and vehicle to the required amount, becomes plugged with grit and flow thereafter stops.

It is accordingly an object of this invention to provide apparatus for distributing a gritty liquid to a lap plate or the like through a small orifice which does not result in plugging of the orifice when the apparatus is in use.

It has also been observed, in lapping machines using a number of wear rings at the same time, particularly when the articles to be lapped are held in the wear rings during the lapping operation, that the stock removal rate of the articles varies as between wear rings. This is particularly true where but one grit and liquid distributing wire is used on the machine. It has been found that the ring nearest the wire will have articles evidencing less stock removal than the next ring to it in the direction of movement of the lap plate, and that the rate of stock removal is progressively less around the lap from the said next or second ring.

Another object of this invention is to provide a grit and liquid distributing apparatus for a lapping machine or the like having a plurality of wear rings or work stations, wherein the gritty liquid is applied equally and uniformly to each station, thus ensuring substantially identical stock removal rates for the articles at each wear ring or station.

As a more specific object, this invention has within its purview the provision of apparatus for distributing a gritty liquid through an orifice which will periodically vary the pressure of the fluid at the orifice whereby to insure an agitation of the gritty particles in the liquid at the orifice and thereby prevent a settling out and accuprincipal components of the grit and liquid distributing system of this invention;

FIG. 2 is a plan view of the portion of the apparatus disposed at the lap plate;

FIG. 3 is anenlarged elevation in section of the orifice and flow dividing means associated therewith, the elevation being taken along line 3-3 of FIG. 2 and in the direction of the arrows at the ends of said line; and

FIG. 4 is an enlarged bottom view of an element of the periodic pressure-varying apparatus.

Referring now to the drawings, there is shown in FIGS. 1 and 2 a horizontally disposed lap plate 10, which is circular in outline and has a flat annular lapping face 11 on the upper surface thereof. Said plate is adapted to be rotated by any suitable means (not shown) about a vertical axis'shown in dot-dash outline at 12. It is con.- templated that there will be three work stations A, B and C on the lap surface, i.e., that articles to be lapped may be placed at three equi-angularly spaced locations on the lap surface 11. It is understood that the number of stations for which a lap plate is designed is not material to this invention nor is the angular spacing of stations.

Disposed above the center of the lap plate 10 is a grit distributing head 13 which may be supported in such location by any fixed frame member (not shown) disposed over lap plate 10. Said head 13 includes a block 14 which is hollow to form a chamber 15 therein (FIG. 3). A threaded opening 16 is formed in the bottom of said chamber into which a fitting 17 is threaded, said fitting having a longitudinal vertically disposed passage 18 extending from one end region thereof to the other. At the upper end region, passage 18 is partially closed by an orifice 19 which, in one embodiment, may be a circular opening in diameter. The diameter of the orifice will vary with the size of the lap plate. At the lower end region, passage 18 terminates in a nozzle 20 the purpose of which is to direct the flow of the gritty liquid to a point immediately below said passage.

Fluid from nozzle 19 is divided into as many streams as there are stations by a distributing head or manifold 21. Since, in the form chosen to illustrate this invention, three stations A, B and C are assumed, manifold 21 is illustrated herein as dividing the fluid from nozzle 20 into three streams. To this end, manifold 21 is comprised of a machined or cast block having a circular recess 22 formed in the upper surface thereof, the side walls of which are threaded to receive the threaded exterior of fitting 17. Three openings 23 are drilled through the bottom of recess 22 to receive the upper ends 24 of three wires 25, the lower ends of which may be bent as shown in FIG. 1 to bring the free ends 26 thereof in proximity to the lap surface 11. The points on the lap surface at which the lower ends terminate and from which gritty liquid is dropped upon the lap surface are selected to ensure the presence of the liquid at the stations A, B and C. Assuming that the lap plate rotates in a counter-clockwise direction as viewed in FIG. 2, the lower free ends 26 are disposed ahead of the work stations.

Openings 23 are of larger diameter than the diameter of the upper ends of wires 25 so that the liquid can fiow out of recess 22 along the wires 25. Upper ends 24 are securely clamped in openings 23 by set screws 27.

The gritty liquid is normally retained in a container 28 which may be removably secured to the lapping machine in the base thereof (not shown). The container 28 is closed by a cover 29 which is likewise removable and to which is secured a motor 30 having a shaft extending downwardly into said container and driving a vaned impeller type pump shown in outline at 31 substantially at the bottom of the container. A pipe 32 connects the outlet of said pump 31 to chamber 15 of 3 distributing head 13, and a pipe 33 connects chamber 15 back to the interior of container 28 through an appropriate opening in cover 29.

Pump 31 serves to maintain a continuous flow of the gritty liquid from container 28, through chamber 15 and back to the container through pipes 32 and 33. The continuous circulation agitates the liquid and maintains the grit in suspension, both in container 28 and in chamber 15. Since the interior of the container is substantially at atmospheric pressure and passage 18 is likewise at atmospheric pressure, there is little or no pressure differential across orifice 19, other than the slight head of fluid in chamber 5 to agitate the liquid in orifice 19 to prevent the grit from settling out and plugging said orifice.

Elimination of plugging is effected by creating a continuous variation in pressure in chamber 15. This is accomplished by periodically blocking the flow of liquid out of pipe 33 into container 28. The blocking means comprises a rotor 34 having one or more vanes 35 and rorated by a small electric motor 36 mounted on cover 29. Vanes 35 rotate in proximity to the outlet of pipe 33 in container 28 and are of such dimension as to interfere with the normal flow of liquid out of pipe 33 and thus create a back pressure in pipe 33 Which is transmitted back to chamber 15 through the fluid in the pipe and chamber. This back pressure creates a pressure differential across orifice 19 and thus agitates the fluid thereat to prevent settling out of the grit and the resultant plugging of the orifice. In the forms illustrated herein, the vanes 35 are approximately 0.005 from the open end of pipe 33. There are two such vanes 35 on rotor 34 and the rotor rotates at approximately 20 rpm.

It has been found that the periodic interruption in flow out of pipe 33 is more effective to keep orifice 1h clear when the quantity of moving fluid in pipe 33 is greater than that in pipe 32. The effect is to fill chamber 15 completely and suddenly, with a sharp momentary rise in pressure therein which serves to dislodge any grit adhering to the orifice. It has been observed that with continuous, uninterrupted flow through chamber 15, orifice 19 actually functions as an aspirator and flow along wires 25 ceases. Return pipe 33 is made larger than outlet pipe 32 and may in fact have approximately twice the cross-sectional areas as pipe 32, so that flow out of chamber 15 is more rapid than flow into said chamber and the change to sub-atmospheric pressure is very rapid.

With gritty liquid flowing intermittently into passage 18 and through nozzle 20 into the bottom of recess 22, continuous streams of substantially equal volume flow out of said recess 22 along wires 25 to lap surface 11. A uniform distribution of grit is thus effected in the vicinity of the work so that parts thereon are uniformly lapped.

It is understood that the foregoing description is merely illustrative of a preferred embodiment of this invention and that the scope thereof therefore should not be limited thereto, but by the appended claims.

We claim:

1. Grit distributin apparatus for a surface-finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, :1 return pipe to the container connected to the chamber to return excess grit and vehicle to said container, an orifice and connected passageway opening out of said chamber, means connected to said passageway for conducting grit and vehicle therefrom to the machine tool, pump means connected to the outlet pipe from the container for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically abruptly varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to force grit and vehicle through said orifice while at the same time preventing blocking of the orifice by an accumulation of grit thereat.

2. Grit distributing apparatus for a surface finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, 21 return pipe to the container connected to the chamber to return excess grit and vehicle to said container, an orifice and connected passageway opening up out of said chamber, means connected to said passageway for conducting grit and vehicle therefrom to the machine tool, pump means connected to the outlet pipe from the container for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to force grit and vehicle through said orifice while at the same time preventing blocking of the orifice by an accumulation of grit thereat, said means for periodically varying the pressure in the first chamber comprising means for periodically obstructing the flow of grit and liquid through the return pipe.

3. Grit distributing apparatus for a surface finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, a return pipe to the container connected to the chamber to return excess grit and vehicle to said container, an orifice and connected passageway opening up out of said chamber, means connected to said passageway for conducting grit and vehicle therefrom to the machine tool, pump means connected to the outlet pipe from the container for transferring the grit and vehicle from the container to the out let pipe, and means for periodically varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to force grit and vehicle through said orifice while at the same time preventing blocking of the orifice by an accumulation of grit thereat, said return pipe having an outlet end extending into the container, and said means for periodically varying the pressure in the first chamber comprising means for periodically reducing the effective area of the said outlet end.

4. Grit distributing apparatus for a surface finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, a return pipe to the container connected to the chamber to return excess grit and vehicle to said container, an orifice and connected passageway opening up out of said chamber, means connected to said passageway for conducting grit and vehicle therefrom to the machine tool, pump means connected to the outlet pipe from the container for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to force grit and vehicle through said orifice while at the same time preventing blocking of the orifice by an accumulation of grit thereat, said return pipe having an outlet and extending into the container, and said means for periodically varying the pressure in the first chamber comprising a vaned rotor disposed eccentrically with respect to the outlet end and adapted to have the vanes thereof pass transversely of the said end and in proximity thereto, and means for rotating the vaned rotor.

5. Grit distributing apparatus for a surface-finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, a return pipe to the container connected to the chamber to return excess grit and vehicle to said container, a second chamber in proximity to the first-mentioned chamber, means connecting said chambers and having an orifice and passageway therein communicating with the first said chamber, means for conducting grit and vehicle from the second chamber to the machine tool, pump means for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically abruptly varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to prevent blocking of the orifice by an accumulation of grit thereat.

6. Grit distributing apparatus for a surface finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, a return pipe to the container connected to the chamber to return excess grit and vehicle to said container, a second chamber in proximity to the first mentioned chamber, means connecting said chambers and having an orifice and passageway therein communicating with the first said chamber, means for conducting grit and vehicle from the second chamber to the machine tool, pump means for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to prevent blocking of the orifice by an accumulation of grit thereat, said second chamber being disposed below the first chamber with the passageway from the orifice above the said second chamber, said means for conducting grit and vehicle from the second chamber being disposed to one side of the passageway, and nozzle means on the end of the said passageway in the second chamber directing the grit and vehicle away from the said conducting means.

7. Grit distributing apparatus for a surface finishing machine tool comprising a container for holding a quantity of grit suspended in a liquid vehicle, a grit distributing head disposed in proximity to the said machine tool, said head having a chamber therein, an outlet pipe from the container connected to the chamber to conduct grit and vehicle to said chamber from the container, a return pipe to the container connected to the chamber to return excess grit and vehicle to said container, a second chamber in proximity to the first mentioned chamber, means connecting said chambers and having an orifice and passageway therein communicating with the first said chamber, means for conducting grit and vehicle from the second chamber to the machine tool, pump means for transferring the grit and vehicle from the container to the outlet pipe, and means for periodically varying the pressure in the first chamber whereby to vary the pressure of the grit and vehicle at the orifice and thus to prevent blocking of the orifice by an accumulation of grit thereat, said second chamber being disposed below the first and being substantially round in horizontal section, said passageway being concentric with the second chamber, a nozzle at the end of the passageway and extending into the second chamber, and said means for conducting grit and vehicle from the second chamber being disposed near the side of said second chamber such that grit and vehicle falls from said nozzle away from said conducting means.

References Cited in the file of this patent UNITED STATES PATENTS 2,069,261 Monnet Feb. 2, 1937 2,839,877 Boettcher June 24, 1956 FOREIGN PATENTS 698,602 Germany Nov. 13, 1940 

